The invention relates generally to automotive vehicle hitch racks and more particularly to a drawbar coupler that provides connection to a tow hitch on an automotive vehicle.
Hitch carrier racks for automotive vehicles are increasingly desirable. Such a rack has a coupler to be received in the receptacle of a receiver-type tow hitch normally used to receive a coupling arrangement for connection to a trailer to be pulled or pushed. Racks commonly support bicycles, ski equipment, or other Sporting or recreational articles. For example, one type of a hitch rack is a hitch rack bike carrier. A hitch bike carrier is a rack which suspends one or more bicycles at the rear of an automotive vehicle (or sometimes at the front of a large vehicle), with the bicycle support structure cantilevered upwardly from a hitch receiver on the vehicle.
Tow hitches are bolted or installed onto holes provided by the automotive vehicle manufacturer.
Typically, these holes are located in the frame of an automotive vehicle. Tow hitches can be installed in the rear, front, or any other portion of the automotive vehicle. Despite the term "tow hitch," the rack, trailer, boat, etc., coupled to this tow hitch via the drawbar coupler is not necessarily towed. The drawbar coupler allows the rack or trailer to be pulled, pushed, or carried in any direction the vehicle is moving.
Four classes of hitches exist to fit almost every automotive vehicle on the road. The most common in past years was the Class I variety of the ball and tongue style of hitch. Recently, however, Class III hitches have become the most popular. Class III hitches differ structurally from class I hitches in that the tongue and ball are replaced by a tubular receptacle (receiver). Because Class III tow hitches are rated to tow 5,000-10,000 lbs, they are flexible enough for a wide variety of applications. They are also aesthetically pleasing. Class II and IV hitches also contain receptacles like the Class III variety and the present invention is equally applicable to these types.
A receiving type of tow hitch normally consists of a square-walled hollow receptacle (often called a "receiver") having a number of bolt holes on its side wails. Various types of couplers provide the connection between this type of tow hitch and the rack or trailer carrying the sporting articles.
Because the manufacturer of the receiving type of tow hitch may not necessarily be the manufacturer of the drawbar coupler, the size of the receptacle on the receiving type of toe hitch must be considered in designing a coupler. Most standard drawbar couplers are fabricated to be smaller than the receptacle hole. Because of the difference in sizes, some free movement, or play, of the drawbar coupler occurs. This play creates unwanted oscillations and vibrations on the rack. In fact, a small amount of play creates a large amount of unwanted oscillations on the rack or trailer. This "amplification" occurs because of the lever-type action of the drawbar. The coupling point of the drawbar and the receptacle acts as a "fulcrum," and, any arc distance traveled by the drawbar far from the fulcrum is relatively great. The recreational equipment or other articles carried by a hitch rack generally are mounted far from the fulcrum. That is, the bars and rails on hitch racks are designed so that the sporting articles are at a certain minimum distance from the automotive vehicle and at a particular orientation relative to the automotive vehicle. Ultimately, the play reduces the life of the rack and the product mounted on the rack or trailer.
Most hitch racks today are designed for a loose fit between the receiving type of tow hitch and the drawbar coupler. Applicant is not aware of the existence of any hardware or mechanism that will alleviate this play. Applicant is only aware of arrangements in which the drawbar coupler is secured to the receiving type of tow hitch with a pin at the surface of the tow hitch. However, this merely keeps the drawbar in place. The lack of any effective tightening of the surfaces allows some shifting of the drawbar within the hitch receiver.
It will be appreciated that because of the cantilever suspension of the bike or other article support structure, a minor lack of rigidity introduced by a joint can be magnified to be a major problem.